JPH04322100A - Manufacture of accelerating tube - Google Patents

Abstract

PURPOSE:To obtain an accelerating tube having the smooth innersurface of each of conjoined portions and its high processing accuracy by conjoining componental parts, and then radiating a fusing beam to the inner surface of the conjoined portion so as to fuse an area near the inner surface of the conjoined portion. CONSTITUTION:An accelerating tube T is set in a beam radiating device 30, the upper and lower positions of the beam radiating device are respectively adjusted by a movable table 32, and then an optical fiber 36 is inserted into the accelerating tube T while the table 32 is being revolved. YAG laser beams are successively radiated along the inner surface of each of conjoined portions J so as to fuse an area near the inner surface of the conjoined portion J. At this time, the optical fiber 36 together with a gas pipe 37 for blowing argon gas upon the inner surface of the conjoined portion J is inserted into the accelerating tube T. Furthermore, an inner tube 38 is set on the accelerating tube T so as to reduce the volume of useless air entered into the accelerating tube T. Air present in the accelerating tube T at the time of radiating the laser beams is replaced by the argon gas, and the argon gas is blown upon the conjoined portion J whereto the laser beams are applied so that the conjoined portion may be prevented from its needles oxidation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a high-frequency accelerator tube using niobium (Nb) or the like for a charged particle accelerator.

0002

[Prior Art] The principle of an accelerator is to adjust the phase velocity of a traveling wave that has an electric field component in the traveling direction of the charged particles so that the charged particles are always in the acceleration phase and are affected by the accelerating electric field. This accelerates charged particles. Among such accelerators, in an accelerator that uses a high-frequency electric field, an accelerating tube is used as a device that generates the high-frequency electric field.

[0003] The accelerator tube is made by cutting or press-molding a superconducting material such as Nb and forming a flange 1 as shown in FIGS. 4 to 6.
, a cell joint part 2, a half-split cell 3 having a small diameter part 3a and a large diameter part 3b, and other components are manufactured, butted against each other, and the joined parts are welded by electron beam welding or the like. Ru. Here, an acceleration tube having one cell as shown in FIG. 7 is referred to as a single-cell acceleration tube 4, and an acceleration tube having a plurality of cells connected as shown in FIG. 8 is referred to as a multi-cell acceleration tube 5.

In order to obtain a high accelerating electric field in such an accelerating tube, it is necessary to suppress discharge from the inner surface of the accelerating tube, and in order to obtain a high accelerating electric field with lower power, Nb
Superconducting accelerator tubes made of superconducting materials such as Furthermore, since the current excited by the high-frequency electric field flows near the inner surface of the accelerator tube, in the case of an accelerator tube manufactured by joining component parts together, there is no possibility of charged particles from jumping out of the tube from the inner surface of the joint, and the charged particles It is important to improve electrical properties to ensure smooth particle flow.

[0005]

[Problems to be Solved by the Invention] However, the conventional method of manufacturing an accelerator tube has the following problems. That is, when welding the component parts by welding, there is a problem in that the manufacturing accuracy of the accelerator tube is reduced due to welding distortion caused by melting of the joint during welding. Additionally, if manufacturing is done by diffusion bonding, plating, or other methods without welding, the possibility of electrical discharge from steps or protrusions that occur at the joint increases, so take measures such as locating the joint in a place where the electric field will not rise. There was a problem in that the joining work was complicated and time-consuming.

The present invention has been made in view of the above points, and it improves the electrical characteristics of the joints of manufactured accelerator tubes, and in particular, makes the joints difficult to discharge, thereby making the joints in areas with low electric fields. It is an object of the present invention to provide a method for manufacturing an accelerator tube that does not require placement and has excellent manufacturing accuracy.

[0007]

[Means and Effects for Solving the Problems] To achieve the above object, the present invention provides a method for manufacturing an acceleration tube in which component parts are joined to each other at a joint portion to form a tubular shape, after joining the component parts to each other. , the melting beam is irradiated onto the inner surface of the joint to melt the vicinity of the inner surface of the joint.

[0008] When the component parts are joined to each other at the joint, a structure is created in which the joined component parts are not deformed by external stress, and handling during and after manufacture is facilitated. As the bonding means, diffusion bonding, plating, metal packing, etc. can be used. When a melting beam is irradiated on the inner surface of the joint of components that are joined together,
By joining, the steps and protrusions that occur at the joints of component parts are melted, the joints become smooth, the electrical characteristics of the inner surface of the acceleration tube are improved, and an acceleration tube with high manufacturing precision and high mechanical strength is created. provided.

[0009] Furthermore, since the melting beam is irradiated onto the inner surface of the joint after the component parts are joined, the irradiation time of the melting beam is shorter than when joining by laser welding, reducing the number of melted parts and reducing the amount of melting. The amount of time the parts are at high temperatures is reduced. Therefore, if the degree of vacuum is the same, the degree of deterioration of the characteristics due to the oxidation caused by absorption of a small amount of oxygen present in the vacuum by the molten zone is reduced, and the electrical characteristics of the molten zone can be improved.

0010

[Example] Below, resonance frequency 2858MHz, mode 2
An embodiment of the present invention for manufacturing a Nb multi-cell accelerator tube of /3π will be described in detail with reference to FIGS. 1 to 3. First, N
The cell part 10 shown in FIG. 2 was manufactured by cutting plate b. The cell part 10 is a substantially cylindrical member, and a small diameter part 10b that protrudes like a flange toward the center in the radial direction is provided around the middle of the large diameter parts 10a, 10a located at both ends.
The peripheral end portion of this large diameter portion 10a becomes a joint J described below.

Next, flanges 11, 11 were arranged at both ends of the cell parts 10, 10, respectively, and abutted against each other, and these were placed in a press device 20 as shown in FIG. The press device 20 arranges a plurality of cell parts 10 and flanges 11 against each other via positioning jigs 24 between a bolster 22 and a slide 23 provided in a vacuum chamber 21, and presses them at high temperature and high vacuum. They are mutually diffusion bonded under certain conditions.

Then, the inside of the vacuum chamber 21 was evacuated using a vacuum pump or the like to create a vacuum inside and outside the acceleration tube made up of the parts 10 and 11. At this time, the inside of the accelerating tube is connected to the vacuum chamber by the gas venting hole 22a provided in the bolster 22.
100 kg with a press 25 at a temperature of 900°C at a vacuum level of 10-6 torr or less, the same as in 1.
/cm2 of pressure and leave it for 5 hours, cell parts 10
, 10 and flanges 11, 11 were diffusion bonded to each other as shown in the figure to produce an acceleration tube.

Next, as shown in FIG. 1, the acceleration tube T manufactured as described above was installed in the irradiation device 30. In the irradiation device 30, a movable table 32 is provided on a base 31 so as to be vertically movable and rotatable, and a cooling water tank 33 is installed on this rotary table 32. In addition, movable table 3
2 is connected with a gas pipe 34 for supplying argon gas into the water tank 33 for substitution. And the accelerator tube T is
As shown in the figure, one end of the flange 11 is fixed to the bottom of the water tank 33 by a fixing member 35, and the water tank 33 outside the acceleration tube T is
The inside is filled with cooling water.

After adjusting the vertical position of the acceleration tube T using the movable table 32, the movable table 32 is moved to 1/2R.
While rotating at a rotation speed of PM (times per minute), the optical fiber 36 is inserted into the acceleration tube T as shown in the figure, and a laser beam of YAG laser light is sequentially irradiated along the inner surface of each joint J. , the vicinity of the inner surface of the joint J was melted. At this time, the optical fiber 36 was inserted into the acceleration tube T together with a gas pipe 37 that sprayed argon gas onto the inner surface of the joint J. Furthermore, a circular tube 38 with a height of 50 cm and an inner diameter of 2 cm was installed above the accelerating tube T to reduce unnecessary air entry into the accelerating tube T.

Therefore, when the inner surface of the joint J is irradiated with the laser beam, the air inside the accelerating tube T is replaced by argon gas, and moreover, the inner surface of the joint J that is irradiated with the laser beam is replaced with argon gas.
is blown with argon gas. Therefore, when the accelerator tube T manufactured in this manner was inspected, it was found that the vicinity of the inner surface of the joint J melted by the laser beam irradiation was shielded from air and was not subjected to unnecessary oxidation.

Furthermore, since the outside of the accelerator tube T was cooled by the cooling water in the water tank 33, only the inner surface of the joint J was melted, and no welding distortion occurred. Moreover, since the vicinity of the inner surface of the joint part J was melted by irradiating the laser beam, the steps and protrusions between the cell part 10 and the flange 11 caused by diffusion bonding in the press device 20 were completely melted, and the welding The vicinity of the inner surface of part J was machined to be smooth without compromising accuracy during assembly.

In the above embodiment, the laser beam was irradiated to the joint in an inert gas atmosphere by flowing argon gas, but if unnecessary oxidation of the component parts can be prevented, it may be possible to irradiate the joint in a vacuum, for example. Needless to say, it's fine.

[0018]

[Effects of the Invention] As is clear from the above explanation, according to the present invention, the inner surface of the joint of the manufactured accelerator tube is smooth, has high processing accuracy, has excellent electrical characteristics, and has high mechanical strength. An accelerator tube is obtained. Moreover, unlike the conventional method, it is possible to arrange the joining portion at any position, increasing the degree of freedom in design, and providing excellent effects such as extremely easy joining work.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the method for manufacturing an accelerating tube according to the present invention, and is a sectional front view when a laser beam is irradiated onto the inner surface of a joint of an accelerating tube.

FIG. 2 is a cross-sectional view of cell parts constituting the acceleration tube of FIG. 1.

FIG. 3 is a cross-sectional front view showing a connection between a cell component and a flange constituting the acceleration tube in FIG. 1;

FIG. 4 shows the components used in the production of a conventional accelerator tube,
It is a perspective view of a flange.

FIG. 5 shows components used in manufacturing a conventional accelerator tube,
FIG. 3 is a perspective view of a cell coupling component.

FIG. 6 shows components used in manufacturing a conventional accelerator tube,
FIG. 3 is a perspective view of a half-split cell.

FIG. 7 is a cross-sectional front view of a single cell accelerator tube manufactured from the components of FIGS. 4 and 6;

FIG. 8 is a cross-sectional front view of a multi-cell accelerator tube manufactured from the components of FIGS. 4-6.

[Explanation of symbols]

10 Cell parts (component parts) 11 Flange (component) J Joint part T Accelerator tube

Claims (8)

[Claims] Claim 1: In a method of manufacturing an accelerator tube in which component parts are joined to each other at a joint part to form a tubular shape, after the component parts are joined to each other, a beam for melting is irradiated to the inner surface of the joint part, and the vicinity of the inner surface of the joint part is A method for manufacturing an accelerating tube, characterized by melting it. 2. The method for manufacturing an accelerating tube according to claim 1, wherein the material of the component parts is niobium. [Claim 3] Joining the component parts by diffusion bonding,
A method for manufacturing an accelerating tube according to claim 1. 4. The method for manufacturing an accelerating tube according to claim 1, wherein the melting beam is a laser beam. [Claim 5] The laser beam is a YAG laser,
The method for manufacturing an accelerator tube according to claim 4. 6. The method of manufacturing an accelerating tube according to claim 4, wherein an inert gas atmosphere is created inside the accelerating tube during laser beam irradiation. 7. The method of manufacturing an acceleration tube according to claim 4, wherein the inside of the acceleration tube is evacuated during irradiation with the laser beam. 8. The method for manufacturing an accelerating tube according to claim 1, wherein the outside of the joint is cooled during laser beam irradiation.